Machine for grinding the blade surfaces of screw propellers



l. D. EBY 2,303,529

MACHINE FOR GRlNDING THE BLADE SURFACES OF SCREW PROPELLERS =Dec, i, 1942,

Filed July 13, 1940 3 Sheets-Sheet l INVENTOR /VAN D. 5)

- BY ;;,M W ATTORNEY D. EBY 2,303,529

MACHINE FOR GRINDING THE BLADE SURFACES OF SCREW PROPELLERS Dec. 1, 1942'.

' Filed July 13, 1940 3 Sheets-Sheet 2" INVENTORL 7 /|/,4/v D. EBY BY 7%fi/f ATTORNEY 'Dec. 1, 1942.

|. D. EB Y MACHINE FOR GRINDING THE BLADE SURFACES OF SCREW PROPELLERS Fii ed July 13, 1940 I 3 SheatsQSheat .3

INVENTOR ll/AN 0, [BY

ATTORNEY Patented cc. 1 1942 UITED MACHINE FOR GRING THE BE SUR- FACES 0F SCREW PROPELLERS 16 Claims.

Th present invention relates to machines for grinding the blade surfaces of screw propellers.

In Patent No. 2,172,368 issued to me September 12, 1939, I have shown a form of recording pitchometer by means of which charts may be made showing the profiles in radial planes of the propeller blade surfaces, so that departures of the actual blade surface from the ideal blade surface may be determined and the blade brought to the best blade surface.

In my copending application Serial No. 294,- 080, filed September 9, 1939 (now Patent No. 2,248,973 of Juy 15, 1941), I have shown an improved form of recording pitchometer for making charts similar to those discussed in the patent and also for making charts showing profiles of a the propeller blade surface at various radii for the same general purposes.

The present invention contemplates a grinding machine adapted to use such charts as guides so that propeller blade surfaces may be ground to produce profiles as near as possible to the ideal profiles.

The present application shows a form of grinding machine designed to have adequate strength for carrying out the grinding operations on propellers of the size used in ocean going ships, preferably constructed in such a way that it can be readily taken apart for shipment from one plant to another. In the form of construction herein shown many of the parts employed are the same as those employed in the form of recording pitchometer'in my copending application above referred to.

Where the grinding is done on smaller 'pro pellers, such as air screws, pump impeller and propeller blades, water wheels and the like, a smaller machine would be employed.

Other and further objects of the invention will appear as the description proceeds.

The accompanying drawings show, for purposes of illustrating the present invention, one of the many embodiments in which the invention may take form, together with modifications of certain parts, it being understood that the drawings are illustrative of the invention rather than limiting the same.

In these drawings:

Figure 1 illustrates a chart of the type Show ing radial profiles of a propeller blade surface;

Figure 2 is a chart oi the type showing profiles of the blade surfaces at various radii;

Figure 3 is a side elevational view of the grinding machine assembled for use on a propeller with blades of right-hand pitch;

Figure 4 is a top plan View of the grinding machine of Figure 3;

Figure 5 is a central sectional view on the line 5-5 of Figure 4;

Figure 6 is a sectional view on the line 6- 6 of l Figures 3 and 1;

Figure 7 is a diagrammatic fragmentary view illustrating an arrangement whereby the machine may be used for recording or testing purposes; and

Figure 8 is a diagrammatic top plan view illustrating a modified form of construction.

The chart i0 shown in Figure 1 has a number of parallel evenly spaced lines H, such as would be the optimum profiles in radial planes of the working face of a true pitch propeller. has a wavy dotted line I: indicating the profile which the rough blade might have in a particular radial plane. In making a chart of radial profiles on the recording pitchometer, as above re ferred to, a chart somewhat like that of Figure 1 would be obtained, but with the lines displaced wherever there was a hump or hollow in the blade surface. The chart would then be removed from the recording machine and the optimum profiles determined by working out on the drawing board the best profile that can be obtained from the one which the rough propeller had. A similar test would be made of all the blades.

In the chart shown in Figure 2 the heavy diagonal lines l3, l4 and I5 illustrate the ideal contours of the working surface of the blade at various radii, the steeper line l3being nearer the root of the blade than the flatter lines at the right. These lines will be straight orslightly curved according to the intent of the designer of the blade. The lines for the back surface of the blades will be curved some as indicated at l6. In the chart obtained from the rough propeller the lines will vary from these ideal contours. The manner of making such charts will be explained later.

The drawings illustrate a propeller P with blade B of right-hand pitch. The propeller hub is placed with the axis vertical, as indicated in the drawings, and it supports a heavy plate 22 by means of spacers indicated at 22'. These parts have provisions, not shown, whereby the center of the plate 22 may be placed exactly over the axis of the propeller.

The plate 22 has a rigid, upwardly extending stud shaft 23 which forms an axle about which the movable parts of the grinder swing. The

shaft 23 receives a ring 24 which supports a graduated sector or protractor 25 adapted to be It also secured to the plate 22 in adjusted angular position by a clamp indicated at 26. The stud 23 also supports a radially swinging arm designated generally by the reference character 30. This radial arm is made up out of two heavy channel shaped bars 3|, 32 secured together by spacers 33, 34 and 35 preferably by welding. The spacers 34 are received on the stud or shaft 23. Upper and lower guides 36 are also preferably welded to the bars or channels 3I and 32. They are accurately ground to shape so as to provide a guideway for a carriage designated generally by the reference character 40'which is movable along the radial arm. This carriage has side plates H and 42 on opposite sides of the arm 30 and carries rollers 43 to secure the carriage to the guides.

The carriage also carries a cross shaft 44 provided with a pinion 45 to mesh with rack teeth 46 carried by the bar 3|. The shaft 42 can be operated by a hand wheel 41 so as to move the carriage back'and forth along the arm 30. The cross member 33 at the outer end of the arm and a bracket 48 near the pivot 23 for th arm rotatably carries a long shaft 49 with keyway 49'. A slidable hand wheel 50 is keyed to the shaft 49 so that it may be turned. The shaft has a worm 5| in mesh with worm teeth 52 on the periphery of the plate 22, so that by manipulating the hand wheel 50 one can swing the arm and parts carried thereby about the propeller axis.

The top 53 of the carriage 40 has a large opening 54, Figures 4 and 6, and this opening is covered by a plate 55 adapted to be secured in adjusted position by clamps 56. When the clamps are loosened the plate 55 can be turned about its center. to adapt the machine for use with a propeller of left-hand pitch.

The plate 55 has a lower, off-center bearing 51 and an upper off-center bearing 58 supported by struts 59. The bearings 51 and 58 receive a vertically movable tube or shaft 60 passing through hole 54 and down between the channels 3| and 32. The lower end of this tube 60 carries a yoke 6I adapted to support an electric motor 62 with grinding wheel 63. This yoke is adjustable about a pivot 64, as will be obvious from Figure 3. The grinding wheel 63 has a working face 65 which is under the center of the plate 55. The workin face of the grinding wheel is adapted to engage the upper face of the propeller blade, as indicated in Figure 6, and, when arm 30 is held immovable and the carriage is moved along the arm, the grinding wheel will move radially, and, if shaft 60 is moved vertically in its bearings. the grinding wheel will travel in a radial plane.

To cooperate with the surface of the propeller it is necessary to vary the vertical elevation of the grinding element, and this is accomplished by controlling the height of the shaft or tube 60. The tube 60 is provided with a number of holes 66 adapted to receive a pin 61 by which the tube can be positively secured to an arm 68 which extends laterally as indicated. This arm has a threaded opening 69 adapted to receive a vertical feed screw I0 having upper and lower bearings, as indicated at H and I2, and carrying a hand wheel I3. By means of the construction just described the shaft or tube 60 can be securely supported in vertical position and moved up and down according to the operation of the feed screw.

The carriage, and parts carried thereby, is heavy and when the swinging arm 30 is supported from the axis. the arm is stiffened by a truss having uprights I4: and tension members I5v It is also connected to a counterbalancing arm I5 carrying a counterweight ll having rollers I8 to travel on the upper guides 19 and connected by ropes and 8i with the carriage so that the counterweight moves away from the axle as the carriage moves out.

The carriage 40 has a laterally extending bracket 84, the outer end of which is provided with a downwardly extending bracket carrying two vertically spaced clamps 86 and 81 for a vertical member 88 to which is secured a guide member 88 having offset upper and lower ends 90 and SI. These are apertured to form vertical guides exactly opposite the center of the shaft 60 and these guides receive a vertically extending rod I29 connected at its upper end by a laterally extending arm I30 with the top of the tube or shaft 60, so that the vertical movements of the tube 60 are imparted to the rod I29. The bracket 84 carries two angle bars I3I and I32 which supports brackets I33 and I34. These brackets carry a T-shaped bar I35 and this bar is provided with a longitudinally reciprocable carrier I36 for an indicator I31.

The carrier I36 is adapted to be clamped to a cord I39. This cord passes around pulleys I40 and I and is connected to the top and bottom of the rod I28, as indicated at I42 and I43. The cord passes around guide wheels, indicated at I44 and I45, so as to extend upwardly and downwardly as will be apparent, these guide wheels being carried on the bracket indicated at I46.

From the foregoing it will be apparent that for any setting of the radial arm 30 over the propeller blade there is a position for the indicator I31 along the guide-I35 corresponding with each elevation of the shaft 60, as determined by the surface of the propeller blade. It is therefore apparent that there is a definite relation between the grinder position and the posililigl of the indicator along the horizontal guide The brackets I33 and I34 rotatably carry a cylinder I50 and a smaller cylinder I5I adapted for paper storage. The storage cylinder is connected to a wind-up motor, such as a phonograph motor indicated at I52, to maintain tension on the paper chart or wrapping W which has one end fastened to the cylinder I50 and the other end fastened to the storage cylinder I5I. The cylinder I50 is provided with a cord receiving drum I54 adapted to receive a cord I55 which passes about a guide pulley I56.

When the apparatus is set up for working with profiles in radial planes, the cord I55 is passed around a guide wheel I56 and secured to an anchorage I51 adjacent the propeller axis so that when the arm 30 is turned relative to the axis no motion will be given the cord as long as the carriage is stationary. When the carriage is moved along the arm from the root of the propeller toward the stop the cord will be pulled off the drum I54 and this will cause the cylinder I50 to rotate and draw the wrapping W from the storage cylinder I5I on to the cylinder I 50. On return movement of the carriage toward the root of the propeller the paper will be automatically rewound on the storage cylinder I5I. In my copending application above referred to the details of construction of the paper storage cylinder and the operating means above referred to are discussed in greater detail.

The plate 22 carries a ring I60 which is marked at each 90 for four-bladed propellers and each for three-bladed propellers. This ring is fitted very tightly in place in the groove which receives it, but can be adjusted when desired. The sector or protractor 25 has a sight opening, indicated at I65 Figure 5, at the same radius as the ring I60. The radial arm 30 carries a bracket I66 which carries a pointer I67 adapted to be moved past the graduations at the edge of the protractor.

While the machine herein is designed primarily for use as a propeller grinding machine which may be altered for use as a recording pitchometer, and, inasmuch as the working record must be made before the grinding operation is performed, and to facilitate understanding the machine, it will be assumed that the grinder mechanism is at the bottom of'the tube 60 of Figure 6 has been replaced by a roller R which is adapted to engage the surface of the propeller and move along this surface in radial planes when the carriage is moved along the guide. It will also be assumed that the pin 67 has been withdrawn so that the shaft or tube 60 may be moved up and down in the bearings 51 and 58. To overcome the weight of this shaft it may be counterbalanced. Assuming that the machine is set up for making the chart, the radial arm 30 is brought to the center line of one of the propeller blades and while in this position the zero of the protractor is brought opposite the zero of the pointer and clamped in position and the ring I60 moved to bring one of its graduations opposite the center of the sight opening I65. The clamp 26 is then released and the arm 30 swung over the other blades and their center lines checked with the graduations on the ring I00. This will show how far the blades are displaced from the proper position, and, if the displacement is not too much, the best compromise set up for the center lines of the blades. The ring and protractor are then reset. Proof marks are then placed on the blades. If a blank piece of paper wound on the storage cylnder I50 is used as a wrapping and a pencil substituted for the indicator I31 one can make charts of the upper surfaces of the propeller blades to indicate the profiles of the blades in predetermined radial planes. These charts will have more or less irregular lines depending upon the unevenness of the propeller blade surfaces. The charts for all the blades are removed and the optimum profiles for each blade determined wth the charts on the drawing board. The charts may be replaced on the cylinders I50 and Il and the grinder substituted for the roller R and the shaft 60 pinned or secured to the arm 68 thereby reconnecting the grinder to the feed screw.

To grind the surtace of the propeller the radial feed mechanism operated by the hand wheel 50 is adjusted to bring the machine into the proper radial plane and the horizontal and vertical feed wheels 41 and 13 adjusted so as to bring the indicator. now substituted for the pencil, to the optimum profile in the particular plane which has been determined from the previously made chart. This process is repeated in each profile until the propeller has been trued along each profile, then the uneven areas are ground to make a smooth surface. After one set of surfaces of the propeller has been trued the machine is removed from the propeller, the pro peller turned over and the other surface trued.

Should the propeller to be worked on be a lefthand propeller instead of a right hand propeller, the hand wheel 41, bracket 48, shaft d9, worm wheel 5| and associated parts are transferred to the opposite side of the arm 30, these parts being fragmentarily shown in dot-and-dash lines in the new position in Figure 4. The bracket 8 with the recording mechanism is removed from the left-hand side of the carriage, as indicated in Figure 6, and replaced on the right-hand side of the carriage, as shown in dot-and-dash lines. The guide wheel I56 and its supporting bracket are moved to-the left side of the carriage. The clamps 56 are loosened so that the disk 55 with parts carried by it can be turned through 180'. These parts are then in the position shown in dot-.and-dash lines in Figure 6, and the grinder is ready for use on a wheel of left-hand pitch.

In some cases it is preferable to operate the recorder mechanism and the grinding mechanism at selected radii instead of at selected angular positions. The apparatus herein shown, with slight alteration, is available for this purpose also. Instead of connecting the cord I55 which operates the paper winding and storage cylinders to a fixed element near the propeller axis so that radial movement of the carriage will effect a winding and unwinding operation of the cylinders, the cord I55 is wound around a pulley I70,

as more clearly shown in Figure 5. This pulley is carried on a vertical shaft I7I mounted on the bracket I66 and provided at the lower end with,

a pinion I72 which is in mesh with the rack I73 secured to the protractor 25 which ha been clamped in place. With this arrangement the moving of the arm about the propeller axis will shift the pinion I12 along the relatively fixed gear I13; and cause the pinion to rotate at an angular speed, depending upon the diameters of the rack and pinion. By selecting a pulley I of the proper diameter it is possible to wind on an amount of cord which corresponds exactly with the length of the are through which the working surface of the grinding wheel 63 (or roller R turned through the from the position of Figure 7) travels at the radius at which the carriage has been clamped. A series of pulley I70 is provided so that by merely changing them one can obtain profiles of the propeller blade surface at selected radii from root to tip. This makes it possible to secure full size,accurate patterns or profiles of the propeller blade surfaces at these radii. A chart such as illustrated in Figure 2 is made in this manner. Here the lines will be positioned along the chart according to the location given the pencil on the guide and the amount of paper which has been wrapped on to the cylinder before the particular line was drawn. The spacings of the lines lengthwise of the chart, have no function other than to facilitate segregating of the chart lines. If along any selected line markings are placed. such as indicated at X, X at a known angular spacing, then the overall pitch between these two points may be accurately checked. The charts of profiles at selected radii are removed from the machine and the optimum outlines determined on the drawing board. The chart are then replaced on the machine and are used as a guide for the grinding operations. In using these charts the carriage is held in positions at the proper radii and the grinding operations are cardied out by adjusting the vertical feed screw and the feed about the axis of the propeller, With this arrangement it is possible to proceed from one blade to the other using the same pulley I10 but without changing the carriage setting on the arm so that the profiles of all the blades at each radius may be made in sequence, suitable adjustment of the pointed carrier I30 along the bar I35 being made by reference to the proof marks placed on the blades.

Where the grinding machine is intended as a part of the equipment of a shop and not to be transported from shop to shop, the machine is provided with a large base plate, such as indicated at 200 in Figure 8. A suitable ring 2|]! is supported above the base plate and this ring, to-

derstood that the particular form shown is but one of the many forms. Various modifications and changes being possible, I do not otherwise limit myself in any way with respect thereto.

What is claimed is:

1. A machine for grinding the blade surface of a screw propeller to conform to optimum profiles as represented by lines on a chart which also bears lines representing the corresponding profiles of the blade surface before grinding, comprising a radially extending swingable arm, a carriage movable along the arm, means for rotatably supporting the arm coaxial of the propeller whereby the arm is adapted to be placed in various radial positions opposite the sloping surface of the propeller blade and the carriage may have angular or radial movement or simul taneously be moved both angularly and radially, a grinder bodily carried by the carriage for movement therewith along the arm and having -a grinding element located to move in a radial line as the carriage is moved along the arm, adjustable mounting means whereby the working surface of the grinding element may be maintained in said planeof. said radial line and the grinder then moved relative to the carriage only in directions parallel with the propeller axis, whereby the grinder may be applied to the propeller blade surface along any selected profile, a chart supporting cylinder bodily movable with the carriage and connected to the chart to wind it thereon, means for rotating the cylindr and chart to position the chart in accordance with one of said movements of the carriage and unaffected by the other of said movements, and a carriage supported indicator opposite the chart, automatically positionable lengthwise of the cylinder in response to the location of the grinder relative to the carriage and adapted to show the relation of the blade surface during grinding to the original blade surface and the desired blade surface. v

2. A machine such as claimed in claim 1, having a stationary worm wheel and an arm carried worm cooperative therewith whereby the arm may be turned about the propeller axis througha complete circle so that the corresponding surfaces of all the blades may be reached.

3. A machine such as claimed in claim 1, having a feed screw for adjusting the position of the grinding element relative to the carriage.

4. A machine such as claimed in claim 1,

wherein the grinder carrying means includes a plate movable about an axis parallel with the ropeller axis and in the radial plane of the grinding element, and eccentrically located supports for the grinder element, whereby the grinder carrying means may be adjusted about said axis for the purposes described.

5. A machine such as claimed in claim 1, wherein the grinder carrying means includes a plate movable about an axis parallel with the propeller axis and in the radial plane of the grinding element, and eccentrically located supports for the grinder element, whereby. the grinder carrying means may be adjusted about said axis for the purposes described, and having a feed screw supported by the plate for adjusting the position of the grinding element relative to the carriage.

6. A machine such as claimed in claim 1, having a second radially extending arm opposite the first and swingable therewith, a counterweight on the second arm and connections between the carriage and counterweight to shift the counterweight toward and away from the propeller axis to correspond with the position of the carriage.

7. A machine such as claimed in claim 1, wherein the chart supporting cylinder and indicator are carried on a bracket fixedly secured to the carriage disposed laterally of the radial plane of the grinding element, the indicator being actuated by a bracket arm extending laterally from the grinder mounting means and partaking of the movement of the grinder relative to the carriage, and a cord shifted by the bracket arm.

8. A machine such as claimed in claim 1, having worm and worm wheel means for securin angular adjustment of the swingable arm, rack and pinion means for securing carriage adjustment along the arm, and feed screw means for adjusting the position of the grinding element relative to the carriage.

9. A machine such as claimed in claim 1, wherein the grinder mounting means, the chart supporting cylinder, the cylinder operating connections, the indicator and its positioning means are detachably secured to the arm and may be mounted in either of two positions relative to the radial plane through the working surface of the grinding element, whereby assembled structure may be used in one arrangement for a righthand pitch propeller and in the other arrangement for a left-hand pitch propeller.

10. Inga machine for grinding the upper blade surface of a screw propeller while disposed with its axis vertical, a radially extending, horizontally swingable arm, means for rotatably supporting the arm above the propeller blade coaxial o! the propeller whereby the arm is adapted to be placed in various radial positions above the sloping surface of the propeller blade, the arm being in the form of a stiff frame with pairs of parallel guides spaced on opposite sides of a median radial plane, a carriage movable along the guides, a carriage-carried, grinder supporting member, ex-

tending vertically between the guides and disposed to one side of said median radial plane, a grinder carried on the lower end of said grinder supporting member, revolving about a horizontal axis at right angles to the radial plane and having a grinding element in said radial plane, and

means for raising and lowering the grinder supporting member and grinder.

11. A machine such as claimed in claim 10, having a carriage carried plate which supports the grinder supporting member, the grinder and the raising and lowering means, said plate and parts carried thereby being adjustable about a vertical axis through the working face of the grinding element.

12. A machine such as claimed in claim 10,

having an arm extending laterally of the grinder supporting member and moved up and down thereby, a horizontally movable carriage supported indicator connected to the laterally extending arm, and adapted to indicate the elevation of the working surface of the grinding element, a rotatable carriage-carried cylinder adapted to carry a blade surface chart, and means to rotate the cylinder in accordance with the movement of the carriage relative to the blade.

13. In a machine for grinding the upper blade surface of a screw propeller while disposed with its axis vertical, a horizontal plate secured above the blade of the propeller and carrying an upwardly extending, coaxially disposed shaft, an arm comprising two parallel horizontal bars spaced on opposite sides of a radial plane through the propeller axis and spacers between the bars, one of the spacers receiving the shaft and acting as a bearing for the arm so that it can swing about the propeller axis, guides carried by the bars, a carriage having side plates outside the guides, the side plates carrying rollers which bear on the guides so that the carriage may be shifted along the arm, the carriage having two vertically spaced bearings above the guides, a vertically slidable shaft in the spaced bearings, the

shaft extending down between the bars and carrying a motor operated grinding wheel, a vertical, carriage supported jack screw adjacent the slidable shaft and a threaded member carried by the slidable shaft and engaging the screw where by the motor and grinding wheel may be raised and lowered.

14. A machine such as claimed in claim 13, having a hand wheel shaft carried by the arm for rotation on an axis parallel with the bars, a worm wheel on the last mentioned shaft and a cooperative worm carried by the horizontal plate whereby controlled angular settings of the radial arm may be made.

15. A machine such as claimed in claim 13, having a rack carried by one of the horizontal bars, a transversely extending hand operated shaft carried by the carriage, and a pinion on the last mentioned shaft for moving the carriage along the radial arm.

16. A machine such as claimed in claim 13, wherein the grinding wheel is laterally disposed with respect to the working surface of the grinding wheel and the vertically spaced bearings, the vertically slidable shaft and the jack screw are bodily adjustable about a vertical axis through the working surface of the grinding wheel.

IVAN D. EBY. 

